stevens



(No Model.) a sheets-sheen 1. I'. M. STEVENS.

VALVE GEAR.

No. 548,598. Patented Oct. 22, 1895.

(No Model.) 2 sheets-sneer 2.

P. M. STEVENS. VALVE' GEAR.

No. 548,598. Patented Oct. 22, 1895.

AN DREW i.GRAHAM.PNOTU-UTHUYWSHNGTUND C UNITED STATES PATENT Ormea.

FRANK M. STEVENS, OE PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO STEPHEN V. GODDEN, OF SAME PLACE.

VALVE-G EAR.

SPECIFICATION forming part of Letters Patent No. 548,598, dated Gotooer 22, 1895, `Application filed August 3,1895. Serial No. 553,085. (No model.)

To all? whom it may concern:

Beit known that I, FRANK M. STEVENS, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Valve- Gears, of which the following is a specification.

My invention relates to a new and useful improvement in valve-gears, but more especially to those known as link motions, and has for its Object to produce a device which when interposed between the eccentric and slide-valve will so alter the motion imparted to the slde-valve from the eccentric as to time the movements of said valve relative to the piston-stroke in such manner as to produce the maximum eltect of the steam upon the piston-head; and with this end in view my invention consists in the details of construction and combination of elements hereinalter set forth and then specifically designated by the claims.

In order that those skilled in the art to which this invention appertains may understand how to make and use the same, I will describe its construction and operation in detail, referring by number to the accompanying drawings, forming a part of this specification, and in which- Figure l represents a portion of a locomotive with my improvement attached thereto; Fig. 2, an enlarged side elevation of the device, the valve and rocker-arms being omitted; Fig. 3, a cross-section at the lineocw of Fig. 2; Fig. 4f, a horizontal section at the line y 'y of said figure; and Fig. 5, a side elevation of the frame of the device, showing the position of the sliding box.

Similar numbers denote like parts in the several views of the drawings.

1 is a frame of such shape as to support the operating parts of the device, and this frame is adapted to be bolted in any convenient manner to the framework of a locomotive about midway of the slide-valve rod.

Formed with the upper portion of the frame 1 is a housing 2, in which is fitted the box 3, so as to have a limited vertical movement, and prevented from withdrawal from said housing` by the yoke 4, held in place by suitable bolts 5, for a purpose hereinafter eX- plained.

6 is a cam pivoted by the bolt 7 to the box 3, so as to be capable of being swung to and fro, as indicated by the double-headed arrow.

8 is a block adapted to slide within the T- shaped groove 9, formed in the frame, and to this block is pivoted the heel of the cam 6 by means of the bolt 10. Thus it will be seen that upon imparting an oscillatory movement to this block the cam will be caused to rock upon the bolt 7, and as the block S can have no vertical motion it follows that the box 3, in which the bolt 7 is fastened, will move up and down within( its housing to compensate for the varying relative positions between the bolt 10 and the bolt 7.

11 is a groove formed inthe cam 6, the contour of its walls being such as to impart a varying motion to the bolt l2, which passes through said slot and is secured by riveting or otherwise in the T-block 13, similar in crosssection to the block S, and adapted to slide in the T-shaped groove 9, so that upon the cam 6 being oscillated, as before described, a to-and-fro motion will beimparted to this block 13 by said oscillations, and this to-andfro movement will be altered and varied by the action of the walls of the cam-slot upon the bolt l2.

In applying this device to a locomotive or other engine the valve-rod is divided and the rear section 14, which is attached to the rocker-arm 15, is pivoted to the cam 6 by the bolt 10 or a suitable sleeve 16, surrounding said bolt, and the front section 17 is pivoted by the bolt l2 to the block 13; or a sleeve 18 may be interposed between said rod and bolt, so that when motion is imparted to the rockerarin by the usual eccentric mechanism, the cam 6 will be caused to oscillate about the bolt 7, transmitting its motion to the valverod 17, plus or minus the motion produced upon said valve-rod by the contour of the walls of the cam-slot 1l.

It is awell-known fact in steam-engineering that the eccentric movement in general used for operating the slide-valve of an engine does not properly time said valve rela- ICO tive to the piston-stroke, and thereby great loss of efficiency is occasioned, since the steam during the portion of its admission to the cylinder is so Wired as to limit its effectiveness upon the piston-head, and also the steam upon the dead side of the piston is not properly freed during its exhaustion and consid.` crable back-pressure is occasioned by the too quick return movement of the valve. These difficulties I have entirely overcome, as by the use of my device I am enabled to s0 time the lap and lead of a slide-valve from the motions of the ecccentric as to cause said valve to dwell or move more rapidly through portions of its travel, thus preventing the Wiring7 of the steam during its admission to the cylinder or exhaustion therefrom, and by al* tering the contour of the walls ofthe cam-slot more or less back-pressure may be had, as occasion may require.

In case it becomes desirable to throvi7 out of action the cam-slot and transmit the movement of the eccentric directly to the slidevalve it is only necessary to remove the bolt 7 and pass a bolt through the hole 19 and screw it into the hole 20, formed in the block 13, which will so connect the cam 6 to the blocks 8 and 13 as to cause it to move therewith in a direct line, which will have the effeet of uniting the sections 14E and 17 of the valve-rod.

While I have shown my improvement as adapted and applied to a locomotive in which a link-reversing gear is used, it is obvious that it is equally' 'applicable to single-eccentric engines.

Having thus fully described my invention, what I claim as new and useful is- 1. In a device of the character described, a frame havinga suitable housing, a block moving vertically in the housing, a cam pivoted to the block, a second block S, moving in a longitudinal groove of the frame, a block 13, slidable in the groove with the block 8, said block 13 having a pin Working in a circular aperture, rods 111 and 17 for transmitting motion to and from the cam as and for the purpose described.

2. In a device of the character described, the frame 1, block 3, having a limited move ment Within suitable housings upon said frame, cam 6, pivoted to said blocks, block S,

sliding Within a groove in 'the frame, and to which the housing of said cam is pivoted, block 13, also sliding in said groove, groove 11, the walls of which are so disposed as to transmit motion to said block 13, and the rods 14 and 17, for transmitting motion to and from said cam, as and for the purpose set forth.

In testimony whereof I have hereunto attixed my signature in the presence of two subscribing witnesses.

FRANK M. STEVENS. Witnesses:

HENRY F. CoLvIN, Pnncv L. BOUCHER. 

